module Physics.Hpysics.BoundingSphere where
import Physics.Hpysics.Types
import Physics.Hpysics.Utils
import Data.List

canIntersect :: Shape -> Shape -> Bool
canIntersect p1 p2 = let
    BoundingVol c1 r1 = boundingVol p1
    BoundingVol c2 r2 = boundingVol p2
    in distance c1 c2 < r1 + r2

constructBoundingSphere :: Shape -> Shape
constructBoundingSphere p = p { boundingVol = BoundingVol zeroVector $ maximum [norm vertex | vertex <- vertices_v p] }

-- | Given /unit/ vector ab, returns barycentric coordinates (wrt a,b) of
-- boundary points of shape's BV.
projectBV :: Vec -> Vec -> Shape -> (FloatType,FloatType)
projectBV a b s = let
    BoundingVol c r = boundingVol s
    project = projectToLineLambda a b
    projectedRadius = r `scale` (b`sub`a)
    v1 = c `sub` projectedRadius
    v2 = c `add` projectedRadius
    in
    (project v1, project v2)